Shooting down the Zeppelin

So shooting down
a bag full of extremely flammable gas the size of a battleship
is really easy. Right?

Wrong!

In 1916, when William Leefe Robinson, Frederick Sowrey and
Wulstan Tempest destroyed the three mighty airships SL11,
L32 and L33, the science and art of air warfare was in its
infancy. The crews of the German airships and the British
flyers who sought to bring them down in fiery ruin both faced
new and potentially fatal problems before they even came to
contemplate fighting each other.

Before considering how to down a Zeppelin we will first think
about the nature of the beast that Robinson, Sowrey and Tempest
had to stalk and kill.

Zeppelins, Their weaknesses and strength

By 1916, Germany was building massive airships of 200 m or
so length capable of flying at about 70 mph at altitudes of
up to about 13,000 feet while carrying 5 tons of bombs and
enough crew to fly the ship, service the engines, patch any
gas leaks and man somewhere in the region of 10 machine guns.
These warships of the skies were kept aloft by a series of
individual hydrogen gas cells cradled within a rigid cage
of metal alloy or in some cases wood all shrouded in a taut
fabric covering.

The average Zeppelin was powered by between 4 and 6 petrol
engines mounted on gondolas which not only moved the ship
through the air but were also used for steering by stopping
and/or reversing engines on one side or the other. Additional
control was provided by rudders. As well as side to side turns
airships had to move up and down. This required the ship to
be carefully balanced or trimmed so that it would react evenly
to the action of elevators. Trim was also controlled by moving
crew around, pumping gas from cell to cell and by jettisoning
water or sand ballast. The trim had to be constantly watched
as changes in air pressure, build up of ice, movement of crew
and loss of hydrogen gas could all upset it. Improperly trimmed,
an airship could easily bounce around the sky like a porpoise.

Violent manoeuvres were impossible in an airship and anything
more than a sedate turn, climb or dive was actually downright
dangerous as the stresses involved in a tight turn could easily
buckle the frame and even tear lifting cells. It is, for instance
believed that the most famous destruction of an airship, that
of the Hindenburgh in 1937, was caused by a sharp turn which
buckled the frame and tore vital gas cells from which the
escaping gas was then ignited by a spark or discharge of static.

Weather could be a very severe problem to an airship although
not as much as it could be to one of the flimsy aircraft of
the day. Even so, high winds and turbulence were a menace
and at the altitudes that the Zeppelins were forced to operate
at temperatures could plummet causing the build up of weight
due to ice forming. The cold temperatures could also freeze
machinery and crew alike causing engine failures and jammed
control surfaces as well as giving exposed crewmen hypothermia
and frostbite. Another problem that was entirely new was that
at their maximum altitude Zeppelin crews could be affected
by a lack of oxygen making them at best dopey and in extreme
circumstances causing oxygen anoxia and unconsciousness. Falls
to certain death were an ever present danger to crewmen clambering
(often in extreme haste) around what was in effect an icy
climbing frame in a 70mph slipstream whilst suffering from
the early stages of hypothermia and anoxia.

An ever present threat was the possibility that the highly
flammable Hydrogen gas which held an airship aloft would catch
fire. A spark from a backfiring engine, an overheating engine
catching fire, a spark from a dropped tool, snapping wire,
electric circuit shorting or even an insane crewman having
a crafty smoke could all easily cause catastrophe. Once alight
a Zeppelin was doomed and there was a negligible chance of
a crew surviving its demise. Parachutes were not normally
carried and even if they had been the chances were that any
one who managed to jump would still be caught up by the vast
flaming wreck as it plummeted to the ground.

By 1916 Germany had a great amount of experience in operating
airships and the crews of the great ships that attacked England
between 1915 and 1917 were a military elite. Commanders such
as Mathy, Peterson and Eckner were well aware of their ships
weaknesses but until Autumn 1916 these commanders and their
crews felt, with some justification, that they could operate
in the night skies over England with relative impunity.

Despite their vast bulk, Zeppelins could be quite stealthy,
cutting back their engines to drift quietly using cloud and
mist for cover. Even if spotted, the height at which a Zeppelin
was flying at could be very difficult to calculate making
most anti aircraft fire (if any was available) wildly inaccurate.
Their stealthy approaches, operational altitude and the fact
that they operated by night also made them difficult to intercept
by the lumbering aircraft available to the British Home Defence
Squadrons of 1916. The advantages that the Zeppelins enjoyed
could also work against them. Operating by night and at high
altitude, precise navigation and identification of targets
was a major problem. No real attempt could be made to bomb
accurately so it was inevitable that they could only cause
terror raids by bombing indiscriminately and causing mainly
civilian casualties.

The trials and tribulations facing the Zeppelin hunters

Zeppelins began to raid England in the Spring of 1915 and
over a year later in Autumn 1916 the British defences had
had negligible success in countering the threat. It was not
through lack of trying.

As noted above intercepting Zeppelins flying by night was
difficult to accomplish. The aircraft available in 1916 were
primitive affairs made of wood, wire and canvas powered by
small and unreliable engine and the machinery to allow a machine
gun to fire forward through a propeller had not been invented.
The BE2c struggled to achieve the altitudes at which Zeppelins
operated and could take an hour or more to get to the right
height. Once at the right height they still had to find their
quarry in a dark sky that was often full of cloud.

Pilots of these aircraft also suffered just as much from
the cold and lack of oxygen as the opposing Zeppelin crews.
An engine failure or lapse of consciousness could easily be
fatal. Navigation was also a severe problem as map reading
was difficult in a dark cockpit by a pilot trying to concentrate
on flying his aircraft. Flying in the dark can be a very disorientating
experience and it can still be relatively simple to make a
fatal error, especially if caught in cloud. Once aloft the
British pilots were alone, there was no sure way to communicate
with the ground so they had to rely on spotting their prey
themselves in a dark sky or follow the tell tale splashes
of anti aircraft fire and searchlights hoping that these were
engaging a real Zeppelin and not an interestingly shaped cloud.

Most dangerous of all, however, was probably the return to
base. Even finding an airfield, let alone the right one, in
the dark could be a problem and landing a plane at night was
considered by most pilots of the period to be at best foolhardy
and accidents, some fatal, were far from uncommon.

Even if a Zeppelin was successfully intercepted they could
still be remarkably difficult to shoot down. Although far
far larger than the average barn door, hitting them with a
machine gun could be remarkably difficult in the dark. It
was difficult to judge the distance, difficult to see where
the gun was pointing or where the shots were going. Being
dazzled by your own muzzle flashes was also not uncommon.
Even if hits were scored the usual solid bullets would normally
just make little holes through which gas would slowly seep.
And that was if a plane actually carried a gun in the first
place! Early attempts at downing Zeppelins were made by pilots
attempting to drop small bombs or explosive darts onto them
from above, not surprisingly with no success.

Between 1915 and 1916 a succession of innovations were introduced
which would make hunting the Zeppelins an easier if only marginally
safer task. These changes were both operational and technological
in nature and would set the ground rules for all future air
defence and night fighting operations.

First find your Zeppelins

Early warning was crucial in making certain that air defences
were alerted and manned in time and that air craft had time
to reach the correct patrol lines and altitudes to have any
chance of successful interception. To some extent the Zeppelins
themselves helped in this as they usually tested their radios
either shortly before or just after un-mooring for a raid.
Interception of these signals could give a crucial few hours
to prepare the defences.
A system of observation posts equipped with binoculars and
listening gear was established. Each was linked to a co-ordinated
command and control network by telephone. These posts would
provide information on where Zeppelins crossed the coast and
in which direction they were moving. Some effort was also
made to estimate their altitude. If these posts successfully
located incoming Zeppelins then they generally gave just enough
time for intercepting fighters to reach the right altitude.

Have a plan. Be in the right place at the right time

Once warned of a raid fighter patrols were alerted and sent
into the air to take up pre allotted patrol positions and
altitudes. This meant that the maximum possible area of sky
was covered and that there was no duplication of effort. The
patrol lines were set to provide the maximum possible chance
of achieving an interception.

Have coordinated defences

In addition to fighter aircraft, by 1916 Britain had developed
true high angle artillery capable of conducting anti aircraft
fire. These were generally grouped in large batteries of guns
covering the major lines of approach to probable targets.
With these guns were placed searchlight batteries to illuminate
incoming Zeppelins and fix their position for the guns and
intercepting planes. Searchlights, guns and further observation
posts and range takers were again connected to a centralised
command post by telephone.

Generally anti aircraft guns were ineffective in hitting
Zeppelins but they often caused Zeppelins to jettison their
bombs prematurely to gain altitude and also indicated where
a Zeppelin was to patrolling fighters.

Have the right plane

The BE2c was hardly the most impressive plane to have ever
flown but it was stable and easy to fly. This made it a good
spotter aircraft but also made it easy to fly whilst at the
same time trying to concentrate on other important matters
such as finding and shooting at a Zeppelin in the dark. Manoeuvrability
was not really needed for this job. Even so, the BE2c's capabilities
were pushed to the limit to even reach the right altitude
to intercept a Zeppelin. To do so the observers seat was removed
and an extra fuel tank installed.

Other alterations that were made to the aircraft flown from
Suttons Farm included the first use of luminous and backlit
dials to make the dashboard visible and a simple little generator
to power the dashboard lights and a map reading lamp with
a shade. In addition one of 39 Squadron's fitters, Sergeant
A.E Hutton, developed an illuminated ring sight that allowed
the gun to be more accurately aimed in the dark.

Have the right weapon

Early attempts to bring down a Zeppelin over England (such
as John Slessor's) were made by getting above the Zeppelin
(Tricky in the low powered BE2c) and drop explosive bomblets
or darts onto it. Wildly inaccurate these attempts failed.
In the beginning shooting at Zeppelins also proved to be ineffective.
Normal solid bullets just made little holes in the vast structure.
Zeppelins also carried a number of dedicated sailmakers tasked
with repairing any such damage caused.

However, by the Autumn of 1916 new ammunition types had been
developed. These were two types of explosive bullet developed
by J Pommeroy and F Brock and an incendiary bullet (Buckingham).
The incendiary round also had the advantage of leaving a streak
of light along its flight path showing where the shot was
going. In effect this was the first use of tracer.

Mixing the ammunition was to sign the death warrant of the
Zeppelins. The explosive Pomeroy and Brock bullets blew gaping
holes in the gas cells releasing large quantities of flammable
hydrogen into the atmosphere to be ignited by the incendiary
Buckingham bullets. The new lit sight developed by Sergeant
Hutton and the glowing tracers of Buckingam bullets also made
hitting the Zeppelins a lot easier.

Later attempts were made with LePrieur rockets strapped to
a planes wings. These were basically giant explosive fireworks
and appear to have ineffective.

Have the right men

The Home Defence Squadrons may have seemed like an easy ticket
to flyers embroiled in the great air combats over Flanders.
The home comforts may have been better in England but it still
took a brave man to risk flying at night, it also took a technically
good pilot able to be able to navigate and fly a plain in
the dark without mishap. The accounts that Leefe Robinson,
Sowrey and Tempest have left us clearly attest to their dedication
in pressing home their attacks despite the difficulties they
faced and in Tempest's case a mechanical failure. These truly
were magnificent men in their flying machines.